Impact mechanism



Dec. 9, 1958 YEAGER 2,863,539

IMPACT MECHANISM Filed Dec. 10, 1956 2 Sheets-Sheet 1 1 2 h INVENTOR.

M LPV/N 4. YEAGEE M. L. YEAGER IMPACT MECHANISM Dec. 9, 1958 2 Sheets-Sheet 2 Filed Dec. 10, 1956 INVENTOR.

m 5 a N NJ United States Patent IMPACT MECHANISM Marvin L. Yeager, Columbus, Ohio, assignor to Herrick L. Johnston, Inc., Columbus, Ohio, a corporation of Ohio Application December 10, 1956, Serial No. 627,376

12 Claims. (Cl. 19230.5)

This invention relates to impact mechanisms and more particularly to the application of a novel mechanism of this type to a motor driven tool for rapidly and etliciently installing and tightening threaded fastenings.

t is an object of the present invention to provide a novel impact mechanism which is simple and compact with a short, rigid spindle of relatively low inertia.

It is another object of the present invention to provide a novel impact mechanism which incorporates a rotating hammer member of relatively high inertia to weight ratio.

It is another object of the present invention to provide a novel mechanism of the type described which assures positive and efficient clutching and declutching operations between a hammer means and an anvil means incorporated in the mechanism.

It is another object of the present invention to provide a novel rotary impact mechanism wherein all parts are diametrically symmetrical so that the mechanism will operate when it is rotatably driven in either direction.

It is another object of the present invention to provide a novel impact tool which includes hammer means, anvil means, and spindle means, said means being compactly and efficiently supported by a novel casing construction.

It is another object of the present inventionto provide an impact mechanism of the type described which incorporates an improved driving mechanism between a motor and a hammer and anvil assembly driven thereby.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred form of embodiment of the invention is clearly shown.

In the drawing:

Figure l is a side elevational view, partially in section, of an impact wrench to which the mechanism of the present invention has been applied;

Figure 2 is an exploded perspective view illustrating the components of the impact mechanism of Figure 1;

Figures 3 through 6 are sectional views, taken substantially along the line 3-3 of Figure 1, with such views being provided to illustrate various stages of the cycle of operation of the impact mechanism of the present invention; and

Figure 7 is a front elevational view of a driving mernber comprising an element of the mechanism of the present invention. 1

Referring next to Figure 1 of the drawing, an impact wrench is illustrated generally at 2th with such tool including a casing means formed by a rear casing portion 21 and a front casing portion 22, the latter being secured to the rear casing portion at the telescoping surfaces 24. Rear casing portion 21 houses a suitable prime mover, such as an air motor, adapted to drive a shaft 26 rotatably carried in a housing 27 containing a suitable bearing means 28.

The motor may be energized or de-energized by means of a suitable trigger 30 mounted on a handle 31 and,

2,863,539 Patented Dec. 9, 1953 since the motor is preferably of a reversible type adapted for operation in either direction, a reversing button is provided on the rear of casing 21 and indicated at 32. Fluid for operating the motor can be supplied through a line 33 shown entering the tool at the bottom of handle 31.

Various sized socket wrenches, not illustrated, may be secured to a conventional socket adapter 35 provided on the forward end of a spindle indicated generally at 36.

With continued reference to Figure 1, and also to the exploded view of Figure 2, the mechanism further includes a hammer cylinder, indicated generally at 38, which is mounted in the forward casing portion 22 by having an outer surface 40 rotatably supported at a casing surface 41 and an inner surface 42 rotatably supported on an outer surface 43 of a bushing 45 the latter being pressed into the forward casing portion to form an integral part of the structure thereof. A bearing ring it! may be provided at the junction of surfaces 40 and 41.

The rear end of spindle 36 includes a hole 50 for slidably receiving a transversely reciprocating pin, or anvil. 51. A hole 53 is formed through anvil 51 with the axis of hole 53 being perpendicular to the path of reciprocating movement of the anvil. Hole 53 is arranged to receive an anvil pin 56 carried on an anvil link 57. It will be noted that anvil pin :36 extends through a slot 59 in the rear end of spindle 36 with slot 59 being shaped to allow the anvil pin 56 to reciprocate perpendicularly to the axis of rotation of the spindle. The anvil link 57 reciprocates back and forth along a rear surface 61 of hammer cylinder 38. As is best seen in Figure 3, anvil link 57 isslidably connected to hammer cylinder 33 at a slot 63 formed in the outer end of the radial arm of link 5'']. Slot 63 is adapted to slidably receive a hammer pin 65 carried by hammer cylinder 38.

Hammer cylinder 38 is providedwith an integrally formed raised portion 68 extending inwardly from surface 42 and terminating in a pair of impact surfaces 70 and 71.. Impact surface 70 is provided for engaging, with impact action, an impact surface 73 provided on an end of anvil51 as best seen in Figure 3. Impact occurs between hammer impact surface 76 and anvil impact surface 73 when the mechanism is rotated in a clockwise direction, as viewed in Figure 3, in a manner later to be described. The other hammer impact surface 71 faces the opposite direction of rotation and is hence arranged to engage the other impact surface 74 provided on the other end of anvil 51. .Hammer impact surface 71 engages anvil impact surface 74 when the mechanism is rotated in a counter-clockwise direction as viewed in Figure 3.

Referring again to Figures 1 and 2, a driving member indicated generally at 76 is mounted on motor shaft 26 at a spline '77 whereby rotation of motor shaft 26 imparts'rotation to driving member 76. As is best seen in Figures 2 and 7, driving member "/6 includes a pair of arcuately shaped portionsfitl and 81. The edge of portion 89 formsa shoulder 82 arranged to engage a radially extending surface 83. on anvil link 57 when the mechanism is driven in a counter-clockwise direction as viewed in Figures 3 through 6. The other arcuate portion forms a second shoulder 85 arranged to drivingly engage a second radially extending surface 86 on anvil link 57 when the mechanism is driven in a clockwise direction as viewed in Figure 3.

It will be noticed from Figure 1 that the forward end of housing 22 contains an annular grease seal 88 at the junction of bearing surface 89, of the spindle, with the bearing surface 90 0f bushing 45.

' As seen in Figure 2, the forward housing portion 22 can be secured to rear housing portion 21 by bolting same thereto at a flange 101 provided with holes 102 for r receiving suitable bo'lts or studs, not illustrated. It will beunderstoo'd that when forward housing portion 22 is removed from rear housing'portion 21 all of the mechanism can be readily removed from andreinserted into the forward housing portion at the opening in the rear end thereof.

For purposes of describing the operation of the present impact mechanism, reference is next made to Figures 3 through 6 which illustrate successive stages in the cycle of operation of the mechanism. An arrow 105 indicates the approximate location and direction of a driving force applied by the previously described shoulder 85 of driving member 76 to surface 86 of anvil link 57. This driving force 105 is split into two smaller forces, one being applied to hammer cylinder 38 at the hammer cylinder pin 65, and the other being applied to anvil 51 at anvil pin 56. If anvil 51 is restrained against lateral movement, as will be the case when the lower end thereof engages the inner surface 42 on the hammer cylinder, as seen in Figure 4, all of the driving force 105 is applied to hammer cylinder pin 65 whereby rotary motion is imparted to hammer cylinder '38. If hammer cylinder pin 65 is locked so it cannot move relative to spindle 36 (as would be the case when impact surfaces 70 and 73 are in contact and spindle 36 is locked, Fig. 3), then hammer cylinder pin 65 acts as a fulcrum and a portion of driving force 105 effects translatory movement of anvil pin 56 and anvil 51 relative to spindle 37 and hammer cylinder 38.

Referring first to Figure 3, the relative positions of anvil 51 and'hammer cylinder 38 indicate that impact surface 70 of the hammer cylinder has just made contact with impact surface 73 of anvil 51. Assuming that sp ndle 36 is locked, as will occur when a threaded fastening has been drawn down against a surface, such contact between the impact surfaces stops the motion of hammer cylinder 38 relative to spindle 36 and allows hammer cylinder pin 65 to act as a fulcrum for anvil link 57. Since driving force 105 is still being applied at surface 86 and increases as the resistance increases, the driving force will move anvil 51 out of the path of impact surface 70. Accordingly, hammer cylinder 38 is released for rotational motion.

Figure 4 illustrates the positions of the elements just after hammer cylinder 38 has been released and transverse movement of anvil 51 has been stopped by the engagement of pin 56 with an end of slot 59 of spindle 36. It should be noted that such transverse movement is stopped prior to engagement of the lower end of anvil 51 with surface 42. This eliminates friction between such lower end of anvil 51 and surface 42. The driving force 105 becomes effective in rotating hammer cylinder 38 at pin 65 with anvil pin 56 acting as a fulcrum for anvil link 57. Rotation of the hammer cylinder 38 is schematically represented by the arrow 107 of Figure 4.

Referring next to Figure 5, hammer cylinder 38 and anvil link 57 are shown rotated through approximately 180 degrees beyond the release position illustrated in Figure 4. A shoulder 110 at the impact surface 70 of the hammer cylinder is illustrated in the course of its movement along an outwardly inclined surface 111 on the lower end of anvil member 51. The driving force 105 applied by driver member 76 to anvil link 57 will then be acting in an upwardly direction as is schematically represented by arrow 105 in Figure 5. Driving force 105, being eccentric to the hammer cylinder pin 65, will then act to shift anvil member 51 upwardly along with the camming action exerted by shoulder 110 on inclined surface 111 on the lower end of anvil member 51. This action serve to move anvil member 51 upwardly whereby it is positively returned to the impact receiving position illustrated in Figure 6. It will be noted that in the configuration of Figure 6 anvil 51 is locked in the upper position illustrated in preparation for an impact blow which takes place approximately 150 degrees of rotation subse- 4 quent to such configuration. The impact configuration occurs when hammer impact surface 70 strikes anvil impact surface 73 as seen in Figure 3.

In considering the operation shown in Figures 3 through 6, it should be noted that during the hammer release process, that is, the action that takes place between the configuration of Figure 3 and Figure 4, the driving motor and driver member 76 rotate faster than hammer cylinder 38. This occurs because some of the rotational movement of the motor is utilized in shifting anvil member 51 downwardly from the position of Figure 3 to the position of Figure 4. During the time that elapses in the cycle of operation between the configuration of Figure 6 and the impact configuration of Figure 3, the hammer cylinder 38 will advance ahead of the driving motor and driving member 76 in preparation for the impact and operations previously described.

With continued reference to Figures 3 through 6, it will be seen that the elements illustrated are diametrically symmetrical whereby rotation of the mechanism in a counter-clockwise direction, as viewed in Figures 3 through 6, may be effected by applying the driving force to the other surface 83 of anvil link 57. When such counter-clockwise operation is being conducted, the other hammer impact surface 71, on hammer cylinder 38, imparts blows to the corresponding impact surface 74 on the lower end of anvil member 51. Hence it will be understood that the operator may selectively institute operation of the device in either a clockwise or counter-clockwise direction by merely actuating the previously described reversing button 32 provided on rear casing portion 21 as shown in Figure 1.

While the form of embodiment of the present invent tion as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow:

I claim:

1. In an impact mechanism the combination of: a rotatably mounted spindle means; rotatably mounted hammer means provided with an impact surface; transversely reciprocally movable anvil means carried by said spindle means, said anvil means including an impact surface; said hammer and anvil means being formed with cam surfaces for moving one of said impact surfaces into a position of impacting engagement with the other of said impact surfaces; and radially extending lever arm means for moving said one surface away from said position of impacting engagement.

2. An impact mechanism comprising, in combination: a motor; a shaft rotatably driven by said motor; a rotatably mounted spindle means; hammer means provided with an impact portion; radially slideable anvil means carried by said spindle means and provided with an impact portion, one of said two impact portions being movable relative to the other of said two impact portions; a link radially connecting said hammer means and said anvil means; means for pivotally securing said link to said anvil means; and means for applying torque from said shaft to said link.

3. An impact mechanism comprising, in combination: a motor; a shaft rotatably driven by said motor; a rotatably mounted spindle means, said spindle means including a hole; an annular hammer means surrounding said spindle means and including an impact surface; an anvil member carried in said hole and radially slideable relative to said shaft, said anvil member including an im-' pact surface; a radially extending member forming a connection between said hammer means and said anvil member; a pin forming a rotatable connection between one end of said radially extending member and said anvil member; means at the other end of said radially extending member in radially slideable engagement with said annular hammer member; and means for applying torque from said shaft to said radially extending member.

4. An impact mechanism comprising, in combination;

a rotatably mounted spindle means; hammer means provided with a first impact surface facing one direction of rotation and a second impact surface facing the other direction of rotation; anvil means carried by said spindle means and provided with a third impact surface facing one direction of rotation and a fourth impact surface facing the other direction of rotation; said hammer and anvil means being formed with cam surfaces for moving said first impact surface radially into a position of impacting engagement with said fourth impact surface; and for moving said second impact surface radially into a position of impacting engagement with said third impact surface, and radially extending lever arm means for moving said surfaces away from said positions of impacting engagement.

5. An impact mechanism comprising, in combination, a motor; a shaft rotatably driven by said motor; a rotatably mounted spindle means; said spindle means including a hole; an annular hammer means surrounding said spindle means and including an impact surface; an anvil member carried in said hole and radially slideable relative to said shaft, said anvil member including an impact surface; a radially extending member forming a lost motion connection between said hammer means and said anvil member; and means for applying torque from said shaft to said radially extending member.

6. An impact mechanism comprising, in combination, a motor; a shaft rotatably driven by said motor; a rotatably mounted spindle means, said spindle means including a hole; an annular hammer means surrounding said spindle means and including an impact surface; an anvil member carried in said hole and radially slideable relative to said shaft, said anvil member including an impact surface; a radially extending member forming a lost motion connection between said hammer means and said anvil member; and a member rotated by said shaft and provided with a shoulder eccentric with said shaft and in engagement with a radially extending surface on said radially extending member.

7. An impact mechanism comprising, in combination, a motor; a shaft rotatably driven by said motor; a rotatably mounted spindle means, said spindle means including a hole; a hammer means surrounding said spindle and including a first impact surface facing one direction of rotation and a second impact surface facing the other direction of rotation; an anvil member carried in said hole and radially slideable relative to said spindle means, said anvil member including a third impact surface for receiving a blow from said second impact surface and a fourth impact surface for receiving a blow from said first impact surface; a radially extending member forming a lost motion connection between said hammer means and said anvil member; and means for applying torque from said shaft to said radially extending member.

8. An impact mechanism comprising, in combination, a motor; a shaft rotatably driven by said motor; a rotatably mounted spindle means, said spindle means including a hole; a hammer means surrounding said spindle means and including an inner wall provided with an inwardly projecting impact portion; an anvil member carried in said hole and radially slideable relative to said spindle means, one end of said anvil member including an outwardly extending impact surface movable into the path of rotation of said impact portion, and the other end of said anvil member including a surface inclined radially outwardly relative to the direction of rotation of said impact portion; a member forming a lost motion connection between said hammer means and said anvil member; and means for applying torque from said shaft to said last mentioned member.

9. An impact mechanism comprising, in combination, a. motor; a shaft rotatably driven by said motor; a rotatably mounted spindle means, said spindle means including a hole; a hammer means surrounding said spindle means and including an inner wall provided with an inwardly projecting impact portion; an anvil member carried in said hole and radially slideable relative to said spindle means, an outwardly extending impact surface facing one direction on an end of said anvil member, and a surface inclined radially inwardly relative to the direction of rotation of said impact portion, said last mentioned surface facing the other direction on said end of said anvil member; a member forming a lost motion connection between said hammer means and said anvil member; and means for applying torque from said shaft to said last mentioned member.

10. An impact mechanism comprising, in combination, a motor, a shaft rotatably driven by said motor; a rotatably mounted spindle means; a hammer means surrounding said spindle means and including an inner wall provided with a first cylindrical surface portion rotatably engaging a cylindrical outer surface of said spindle means, a second cylindrical hammer surface portion of larger radius than the first-mentioned hammer surface portion, and an impact shoulder at the junction of said surface portions of said inner wall; an anvil member movably carried by said spindle means, said anvil member being formed with an impact shoulder at one end thereof, a sloped surface on the other end of said anvil member for moving said anvil member radially outwardly between a position wherein said anvil shoulder lies radially inwardly of said first cylindrical hammer surface portion and a second position whereat said anvil shoulder lies radially outwardly of said first cylindrical hammer surface portion, and means for applying torque from said shaft to said hammer means to impart rotary motion thereto, said means including a radial lever arm pivotally secured to said anvil for disengaging said impact surfaces.

11. The combination of a rotatably mounted hammer member formed with a stepped cylindrical bore having small and large radius portions which meet to form hammer faces, a rotatably mounted spindle member having a transverse cylinder and a cylindrical surface formed to fit said small radius portion, a reciprocating anvil piston mounted in said cylinder and having a length greater than the chord between the high points of said faces but smaller than the chord between the low points of said faces, said anvil being formed with impact-receiving faces on one side of each end and lifting surfaces on the other side of each end and inclining outwardly and toward said impact receiving faces, and means including a pin secured to said anvil cylinder and an arm between said pin and said hammer for positively shifting said anvil cylinder.

12. The combination in accordance with claim 11, wherein said arm is radial, and another pin secured to said hammer, the outer end of said arm being slot-ted to receive the last-named pin, and means for applying force at a point in said arm between said pins, whereby the hammer pin acts as a fulcrum when said lever arm moves the anvil pin in translation to declutch anvil and hammer and whereby said anvil pin acts as a fulcrum when the lever moves said hammer pin to drive said hammer.

References Cited in the file of this patent UNITED STATES PATENTS UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2,863,539 December 9, 1958 Marvin L Yeager It is 7=-:-':' -i5;by certified that error appears in the printed specification of tlde numbered patent requiring correction and that the said Letters vPatent should read as corrected below.

Column 4, line 16, after "the impact and" insert declutching Signed and sealed this 12th day of May 1959.

(SEAL) Attest:

KARL H. AXLINE Attesting Oflicer ROBERT C. WATSON Commissioner of Patents 

